1. Field of the Invention
This invention relates to electrophotographic photosensitive members and use thereof, and more particularly, to those containing a novel organic photoconductive material.
2. Description of the Prior Art
There have so far been known electrophotographic photosensitive members in which inorganic photoconductive materials such as selenium, cadmium sulphide, and zinc oxide are utilized as photosensitive components.
On the other hand, many kinds of organic photoconductive materials have been developed since specific organic compounds were found to exhibit photoconductivity. The organic photoconductive materials hitherto disclosed include; polymers, e.g. poly(N-vinylcarbazole, polyvinylanthracene and the like; low molecular compounds, e.g. carbazole, anthracene, pyrazoline compounds, oxadiazole compounds, hydrazones, polyarylalkanes and the like; and pigments or dyes, e.g. phthalocyanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, perylene pigments, indigo dyes, thioindigo dyes, and methine dyes derived from squaric acid. In particular, various organic photoconductive pigments and dyes have been proposed for reasons such that these organic materials are easy to synthesize as compared with inorganic photoconductive materials and additionally a compound having suitable spectral sensitivity may be selected from a wide variety of organic photoconductive materials. For example, electrophotographic photosensitive members disclosed in U.S. Pat. Nos. 4,123,270, 4,247,614, 4,251,613, 4,251,614, 4,256,821, 4,260,672, 4,268,596, 4,278,747, and 4,293,628 comprise two laminated photosensitive layers which function respectively as a charge generation layer and a charge transport layer, wherein a photoconductive disazo pigment is used as a charge-generating material.
Electrophotographic photosensitive members employing such organic photoconductive materials can be produced with extremely high productivity and at low costs because the production thereof is possible by coating method with aid of a binder suitably selected, and are further advantageous in that the working wavelength region is freely controllable by varying organic photoconductive pigments or dyes. On the contrary, these photosensitive members have difficulty in the sensitivity and durability, so that those put into practical use until now are extremely limited.